A multi-Input Multi-Output (MIMO) or multi-transmitting multi-receiving antenna technology is a major breakthrough of antenna technologies in the field of wireless mobile communications. This technology, which is a key technology that must be adopted by a new-generation mobile communication system, can increase in multiples the capacity and the spectrum efficiency of a communication system under the condition that the bandwidth is not increased. The MIMO technology allows a plurality of antennas to simultaneously transmit and receive a plurality of spatial streams (frequency bands), and can identify signals transmitted to or received from different spatial orientations. By virtue of the application of a multi-antenna system, parallel data streams can be transmitted at the same time. In addition, the adoption of multiple antennas at a transmitting end or a receiving end can obviously overcome channel fading and reduce an error rate.
However, terminal equipment, particularly a handheld terminal, is limited by the appearance and the size of the product, so it is hard to implement multiple antennas in a terminal product. To solve the technical problem, a conventional method is to set mutual distances between the multiple antennas as far as possible to make the separation degree between every two adjacent antennas large enough; such a layout can achieve a certain effect. However, at present, there has been higher and higher requirement on the appearance of the terminal products, and the minimization of the products has become an irresistible trend of the future. This trend leads to a result that the distances between the antennas cannot be set ideally, and the interference between the multiple antennas cannot be avoided. A main reason of the interference is that all the antennas are in common ground connection with a Printed Circuit Board (PCB). When two adjacent antennas receive signals, an extremely high coupling current will be formed between feeds of the two antennas, and it leads to mutual interference between the two adjacent antennas.
Thus, how to prevent mutual interference between multiple antennas when the terminal is small in its physical size has become a problem to be solved in an urgent need at present.